| /* Optimized strcmp implementation for POWER7/PowerPC64. |
| Copyright (C) 2010 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA |
| 02110-1301 USA. */ |
| |
| #include <sysdep.h> |
| #include <bp-sym.h> |
| #include <bp-asm.h> |
| |
| /* See strlen.s for comments on how the end-of-string testing works. */ |
| |
| /* int [r3] strncmp (const char *s1 [r3], |
| const char *s2 [r4], |
| size_t size [r5]) */ |
| |
| EALIGN (BP_SYM(strncmp),4,0) |
| CALL_MCOUNT 3 |
| |
| #define rTMP r0 |
| #define rRTN r3 |
| #define rSTR1 r3 /* first string arg */ |
| #define rSTR2 r4 /* second string arg */ |
| #define rN r5 /* max string length */ |
| /* Note: The Bounded pointer support in this code is broken. This code |
| was inherited from PPC32 and and that support was never completed. |
| Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */ |
| #define rWORD1 r6 /* current word in s1 */ |
| #define rWORD2 r7 /* current word in s2 */ |
| #define rWORD3 r10 |
| #define rWORD4 r11 |
| #define rFEFE r8 /* constant 0xfefefefefefefeff (-0x0101010101010101) */ |
| #define r7F7F r9 /* constant 0x7f7f7f7f7f7f7f7f */ |
| #define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f7f7f7f7f) */ |
| #define rBITDIF r11 /* bits that differ in s1 & s2 words */ |
| |
| dcbt 0,rSTR1 |
| or rTMP,rSTR2,rSTR1 |
| lis r7F7F,0x7f7f |
| dcbt 0,rSTR2 |
| clrldi. rTMP,rTMP,61 |
| cmpldi cr1,rN,0 |
| lis rFEFE,-0x101 |
| bne L(unaligned) |
| /* We are doubleword alligned so set up for two loops. first a double word |
| loop, then fall into the byte loop if any residual. */ |
| srdi. rTMP,rN,3 |
| clrldi rN,rN,61 |
| addi rFEFE,rFEFE,-0x101 |
| addi r7F7F,r7F7F,0x7f7f |
| cmpldi cr1,rN,0 |
| beq L(unaligned) |
| |
| mtctr rTMP |
| ld rWORD1,0(rSTR1) |
| ld rWORD2,0(rSTR2) |
| sldi rTMP,rFEFE,32 |
| insrdi r7F7F,r7F7F,32,0 |
| add rFEFE,rFEFE,rTMP |
| b L(g1) |
| |
| L(g0): |
| ldu rWORD1,8(rSTR1) |
| bne cr1,L(different) |
| ldu rWORD2,8(rSTR2) |
| L(g1): add rTMP,rFEFE,rWORD1 |
| nor rNEG,r7F7F,rWORD1 |
| bdz L(tail) |
| and. rTMP,rTMP,rNEG |
| cmpd cr1,rWORD1,rWORD2 |
| beq L(g0) |
| |
| /* OK. We've hit the end of the string. We need to be careful that |
| we don't compare two strings as different because of gunk beyond |
| the end of the strings... */ |
| |
| L(endstring): |
| and rTMP,r7F7F,rWORD1 |
| beq cr1,L(equal) |
| add rTMP,rTMP,r7F7F |
| xor. rBITDIF,rWORD1,rWORD2 |
| |
| andc rNEG,rNEG,rTMP |
| blt L(highbit) |
| cntlzd rBITDIF,rBITDIF |
| cntlzd rNEG,rNEG |
| addi rNEG,rNEG,7 |
| cmpd cr1,rNEG,rBITDIF |
| sub rRTN,rWORD1,rWORD2 |
| blt cr1,L(equal) |
| sradi rRTN,rRTN,63 |
| ori rRTN,rRTN,1 |
| blr |
| L(equal): |
| li rRTN,0 |
| blr |
| |
| L(different): |
| ldu rWORD1,-8(rSTR1) |
| xor. rBITDIF,rWORD1,rWORD2 |
| sub rRTN,rWORD1,rWORD2 |
| blt L(highbit) |
| sradi rRTN,rRTN,63 |
| ori rRTN,rRTN,1 |
| blr |
| L(highbit): |
| srdi rWORD2,rWORD2,56 |
| srdi rWORD1,rWORD1,56 |
| sub rRTN,rWORD1,rWORD2 |
| blr |
| |
| |
| /* Oh well. In this case, we just do a byte-by-byte comparison. */ |
| .align 4 |
| L(tail): |
| and. rTMP,rTMP,rNEG |
| cmpd cr1,rWORD1,rWORD2 |
| bne L(endstring) |
| addi rSTR1,rSTR1,8 |
| bne cr1,L(different) |
| addi rSTR2,rSTR2,8 |
| cmpldi cr1,rN,0 |
| L(unaligned): |
| mtctr rN |
| ble cr1,L(ux) |
| L(uz): |
| lbz rWORD1,0(rSTR1) |
| lbz rWORD2,0(rSTR2) |
| .align 4 |
| L(u1): |
| cmpdi cr1,rWORD1,0 |
| bdz L(u4) |
| cmpd rWORD1,rWORD2 |
| beq cr1,L(u4) |
| lbzu rWORD3,1(rSTR1) |
| lbzu rWORD4,1(rSTR2) |
| bne L(u4) |
| cmpdi cr1,rWORD3,0 |
| bdz L(u3) |
| cmpd rWORD3,rWORD4 |
| beq cr1,L(u3) |
| lbzu rWORD1,1(rSTR1) |
| lbzu rWORD2,1(rSTR2) |
| bne L(u3) |
| cmpdi cr1,rWORD1,0 |
| bdz L(u4) |
| cmpd rWORD1,rWORD2 |
| beq cr1,L(u4) |
| lbzu rWORD3,1(rSTR1) |
| lbzu rWORD4,1(rSTR2) |
| bne L(u4) |
| cmpdi cr1,rWORD3,0 |
| bdz L(u3) |
| cmpd rWORD3,rWORD4 |
| beq cr1,L(u3) |
| lbzu rWORD1,1(rSTR1) |
| lbzu rWORD2,1(rSTR2) |
| beq L(u1) |
| |
| L(u3): sub rRTN,rWORD3,rWORD4 |
| blr |
| L(u4): sub rRTN,rWORD1,rWORD2 |
| blr |
| L(ux): |
| li rRTN,0 |
| blr |
| END (BP_SYM (strncmp)) |
| libc_hidden_builtin_def (strncmp) |
